Here’s a fun video showing the rainbow of colors that anodized titanium can become. There are blues and purples and gold and it all changes so fast. It’s basically magic (or science!) that just applying voltage to a piece of titanium in an electrolytic bath can transform the color completely.
Anodizing titanium is a process that adjusts the oxide level of metal surfaces. This adjustment changes the spectrum of light, resulting in perceived color. By precisely controlling the surface oxide level, an entire range of colors can be produced.